1. Field of the Invention
This invention relates to a connecting method and a connector for wiring and connecting, in particular cross-wiring flexible planar conductor cables.
2. Statement of the Prior Art
A flexible planar conductor cable or a flexible printed circuit (hereinafter referred to as "FPC") has a construction in which a circuit pattern is formed by attaching a conductor such as Cu or the like through an adhesive on an insulation film such as polyimide or the like and a similar insulation film is applied through an adhesive to the former film with the circuit pattern.
Such an FPC is easily wired since it is flexible and the conductors are formed in a pattern on the film. In particular, FPCs are often used to interconnect complicated circuits and devices. However, it is impossible to cross-wire an FPC so that it jumps over a circuit pattern, since it is formed with a planar shape whereby circuit design is subject to various restrictions.
For example, if a circuit design is effected to eliminate cross-wiring the circuit pattern of a portion to be connected to FPC devices are predetermined and thus the devices to be connected to the FPC must accord with the circuit pattern of the FPC. Consequently, design of devices is subject to serious limitations. Accordingly, it is necessary to effect cross-wiring on an FPC. A prior method of cross-wiring an FPC employs a jumper lead.
For convenience of explanation, an example of the prior method of cross-wiring of the FPC is described below with reference to drawings. FIG. 19A is a plan view of a cross circuit, FIG. 19(B) is a circuit pattern for carrying out the wiring of the cross circuit, and FIG. 19(C) is a partial cross sectional view of a circuit wired with a jumper lead.
In the case of designing, for example, a circuit pattern of an FPC in accordance with a wiring diagram shown in FIG. 19(A), there are three cross circuits A, B, and C. FIG. 19(B) shows a circuit pattern of conductors 3 of the FPC to realize the above circuit diagram and the jumper leads are used as shown by broken lines 3a, 3b, and 3c. As shown in FIG. 19(C), jumper lead 2 is disposed under FPC 1, one end of jumper lead 2 projects from connecting hole 3e formed in a connecting portion of Cu pattern 3, these portions are soldered by solder 4 to complete the cross-wiring.
In FIG. 19(C), 1a is an insulation film, and 1b an adhesive, and 1c an insulation film provided on the rear side thereof.
However, in the conventional cross-wiring using the jumper leads it is required to carry out steps of forming holes 3e in the connecting portion of FPC 1, inserting jumper leads 2 into holes 3e from the underside of the FPC, and then soldering them. Thus, it is very difficult to change the circuit pattern of the cross-wiring on account of the soldering of jumper leads 2 and the connecting portion of the FPC. It is also impossible to change the circuit pattern of the FPC conductor only by changing the circuit of the jumper leads 2 since a predetermined circuit pattern of the conductor of the FPC is formed on a portion having no cross-wiring (for example, portion 3d in FIG. 19(B)). Further, there is a case where the circuit pattern itself of the FPC conductor must be changed.